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Tuesday, February 08, 2011

A Disquisition on the Nature of Sour

I'm not totally sure why tastes are broken down into just five categories (salty, sweet, sour, bitter, and umami), but what's interesting is that two of the three most characteristic beer flavors--sour and bitter--are considered "aversive." That is, they are signals our ancient adaptive brains recognize as containing potentially lethal substances. These categories of taste are subjective and culturally specific. So much of the terrain of flavor exists well outside their small purview--but somehow they persist.One of these flavors is the subject of today's post: sour. What is sour, and when should it apply to flavors found in beer, and particularly, should we consider brettanomyces-inoculated beer sour? The answer is semantic, not scientific, but that's fine: it's best to have a shared vocabulary in discussing the flavors present in beer. Back when I reviewed this year's Dissident, I classed it as a sour beer, and Ezra took issue with this. A few weeks ago, the Brewers Association signaled they were in accord with Ezra's view and split brett-inoculated beer off from the category of "sour." And then last week, when I was chatting with John Harris, he also made the point. So, what's sour?

The Nature of SourWhat we call "sour" is the perception of acids. Vinegar, is a great example; it takes most of its sour quality from acetic acid, but also has small amounts of citric acid and tartaric acid. In beer, lactic acid is a big player in the perception of sourness. Impressionistically, it's that puckery quality. Linguistically, there's no precise distinction between "tart" and "sour," though beer people will typically ascribe to more lightly-soured beer the adjective "tart." I'm cool with that.

The Nature of WildWild ales almost always produce sour flavors, but they usually produce lots of other flavors, too. Many of these are referred to by similarly wild-sounding adjectives: horse-blanket, zoo-like, goaty, sweaty. Other qualities seem to come from chemistry labs: nail-polish remover, paint thinner, etc. Still others are less precise--dusty, austere, hot, sharp, funky, tangy. The process of fermentation produces lots of chemical by-products, and no doubt a sophisticated lab could identify all the compounds that produce these varying flavors. Some are related to sourness, some are miles away. I have been lax about using the words "sour" and "wild" interchangeably, and this definitely confuses matters. If a beer is zoo-like, it's best not to refer to it as sour.

Is Brettanomyces Sour?So then we come back to our friend, brett. Many of the qualities it produces aren't traditionally sour. But it can produce sour notes. At halftime of the Super Bowl, we cracked a Billy the Mountain--a beer soured with brettanomyces clausenii. (The Packers were ahead and I wanted to celebrate while we had the chance--no waiting until the end of the game for this pessimist!) And yes, it is sour--or at the very least notably tart. In fact, the signature quality the brett contributes to the Billy the Mountain is tartness/sourness (though there are other, more subtle harmonics, that figure in). This isn't always the case--this year's Dissident, for example, has many wild qualities, but its acid is less sour than dry and leathery. One of the by-products of brettanomyces is acetic acid, though it doesn't always crank it out in huge quantities. Beers made with brett can therefore be sour or not. They are the chimera of the sour world.

The upshot to all of this is that I feel suitably chastened about my cavalier substitution of the word "sour" for "wild." As a matter of coming to shared vocabulary, using the word sour should be restricted to flavors that are, in fact, sour. On the other hand, it is not strictly true that brett beers are not sour, either. (Claiming they're just "tart" is a scoundrel's refuge.) This is especially true when we're trying to come to shared vocabulary. Compared to standard beers, something like Billy the Mountain has to be considered sour. It's an abstraction to exempt it because the sourness is lighter, different, and more subtle than in other soured ales--and to the average beer drinker, a bizarre elision.

In conclusion, to the question "are brett-inoculated beers sour?" we must agree to the answer "yes." And "no." Thank your for your attention.

You hit the nail on the head with the second to last paragraph. A beer should be considered sour in comparison to the drinkers standard beer of choice. A beer with a light "tartness" is sour to me but probably not to someone who chooses straight lambic as their drink of choice. Great commentary.

I know I am very late to the party, but I'll comment nonetheless since this topic is on my mind quite often. I'm in the camp that does not like to use the term sour as a noun either (good commentary on that, though, fellas) because there are so many more flavors available in the wide ranging beer styles we are talking about here.And there are many levels of tart/sour. And, what do you call a brett fermented beer that does not taste sour?? As mentioned, we don't call hoppy beers bitters (oh wait, in the UK they do) but we don't call malty beers 'sweets'. That doesn't make sense to me. I read somewhere that Charlie Papazian had a Belgian brewer ask, "why do Americans call these beers 'sour beers'? He was mystified. In his book, Wild Brews, Jeff Sparrow refers to some of the beers as acid beers or Flanders acid beers. And of course the title of his book indicates that Wild beers would be an appropriate name. I wish we could just call them what they are, Flanders, gueze, lambic, kreik, peche, frambozen, flemish brown AND if we make something that does not fall in those categories, make up a style name (hey can I hear my CDA brethren calling??) Something besides 'sour ales' mind you. For me, I like Wild ales and will use that at Oakshire. As much as I love my friends at Cascade Brewing and the wonderful barrel house they built in SE Portland, I shutter every time I see there sign outside that I believe says 'Barrel Aged sour ales' (I may be mistaken on that). If something is just 'tart' or they serve other Cascade lodge beers there, someone is going to bitch. ( I really hope my opinion on this does not bar me from more personal tours with Preston or Ron, because my last two were sweet! Love you guys....)Anyway, perhaps this all boils down to what we in America need as a craft beer drinking country, a style name for everything, or more importantly an answer for the question, "What does it taste like?" Good post, Jeff. I'm looking forward to the day that people stop asking, "what are the IBUs?" and instead ask "what is the Ph?"cheers!